Startup Devises Liquid Metal Batteries for the Electricity Grid

A Boston-area startup has invented new liquid-based heavy-duty battery technology that its founders hope will be the foundation of the next-generation electricity grid in which alternative energy will play a key role. Ambri -- yet another company formed out of that bastion of modern invention, the Massachusetts Institute of Technology (MIT) -- is developing giant cells that are comprised of liquid electrodes and an electrolyte capable of storing large amounts of solar and wind power at a low cost.

The battery is the brainchild of Donald Sadoway and Ambri CTO David Bradwell, co-founders of the company that developed the technology at MIT in the lab of Sadoway, a professor of materials chemistry there.

As Sadoway explained last year at a TED conference -- a talk posted in a video on the company’s website -- he worked for about six years to come up with a battery chemistry that could meet the intensive needs of the power industry, which are “uncommonly high power, long service lifetime, and super-low cost.”

David Bradwell (left) and Donald Sadoway are co-founders of Ambri, a Cambridge, Mass.-based startup that is developing a liquid-based battery they hope will be the foundation for the next-generation electricity grid. (Source: MIT)

“With a giant battery, we could address the problem of intermittency that prevents wind and solar from contributing to the grid in the same way that coal and gas and nuclear do today,” Sadoway said. “The battery is the key enabling device here. With it we could draw electricity from the sun when the sun doesn’t shine.”

He employed Bradwell -- then a post-doc at MIT -- to create the battery from his concept of using metals that when heated form liquids that are the basis for the battery, using a low-density liquid metal at top, a high-density liquid metal at bottom with a layer of molten salt in between as the electrolyte. The first battery created by Sadoway and Bradwell used magnesium at the top as the negative electrode and antimony at the bottom as the positive electrode.

The chemistry works like this: When the battery discharges power, magnesium atoms give off electrons that travel through the salt layer and react with the antimony. This forms an alloy and expands the bottom layer of the cell, or the cathode. To charge, the battery itself acts like a metal smelter, separating the magnesium from its alloy back through the electrolyte to return to the magnesium. In this way, too, the battery self heats, which keeps the metals liquid.

Ambri has since started using less expensive and higher voltage metals and salt for the battery, but it continues to work in the same way, according to the company. Eventually the cells will be stacked into modules the size of 40-ft shipping containers with “the nameplate capacity of two megawatt-hours -- 2 million watt-hours,” Sadoway said. “That's enough energy to meet the daily electrical needs of 200 American households,” he said. “So here you have it, grid-level storage: silent, emissions-free, no moving parts, remotely controlled, designed to the market price point without subsidy.”

Ambri is not the only company that’s invented new technology that could allow energy generated by wind and solar sources to take a more central role in the utility grid. Automation vendor ABB said recently it had solved a longtime problem of how to transport power over long distances with the design of the first circuit breaker for high-voltage direct current, or HVDC. This would allow for connections between large wind farms and solar power grids from different places to be plugged into the traditional power grid, the company said.

You have a valid concern, Greg, and I imagine the founders of Ambri saw it that way, too. They're now using a different chemistry for the battery that has a similar result. Perhaps they ran into the antimony problem as well! I am not sure they are disclosing the battery chemistry (probably for IP reasons). I think the new chemistry is more cost effective and higher voltage (I mention it in the story). Thanks!

Great article and innovative use of new materials. One concern I have would be the current lack of Antimony availability outside of China. Some of the information I'm reading states that no significant new antimony deposits in China have been developed recently and other economic reserves are being depleted.

I can see it leading to direct to consumer products for urban dwellers who rent. It's a growing market in the US. Many people would love to put solar panels in or near a window and use that energy to power both small and large appliances.

I know that versions of that already exist for cell phones, ipods, etc. Many green consumers would jump at the chance to power up a refrigerator off the grid.

This is the kind of thinking that really has exciting possibilities if its potential can be fully realized. No longer will alternative energies be excluded from large-scale power grids if energy can be stored in this way and meet the low-cost needs of the industry. It really could revolutionize the use and generation of the energy not just in the United States, but worldwide. I applaud inventors like Sadoway and his team who are really trying to solve the energy crisis not with rhetoric but true scientific invention.

It won't be too much longer and hardware design, as we used to know it, will be remembered alongside the slide rule and the Karnaugh map. You will need to move beyond those familiar bits and bytes into the new world of software centric design.

People who want to take advantage of solar energy in their homes no longer need to install a bolt-on solar-panel system atop their houses -- they can integrate solar-energy-harvesting shingles directing into an existing or new roof instead.

Kaspersky Labs indicated at its February meeting that cyber attacks are far more sophisticated than previous thought. It turns out even air-gapping (disconnecting computers from the Internet to protect against cyber intrusion) isn’t a foolproof way to avoid getting hacked. And Kaspersky implied the NSA is the smartest attacker.

Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.